Uneven lawn and weeds

Hello. Got two topics that need advice. First, is there any way of leveling uneven lawn. Over the years I have extended the lawn by taking out overgrown borders. But where the new lawn meets the old lawn there is a hollow. Second issue. The lawn is quite good except for the weeds. A variety of weeds. What I would like to know is are there any Pet Friendly weed killers. I have spent time digging out the larger weeds, but this leaves holes in the grass where our 2 puppies think it's a good place to start digging.

i want to level my lawn it dips in plases what sand and compost do i use

You dont necessarily need sand and compost------

There are two ways-lift the turf and lay some soil up to the level you want and replace turf for a quick fix or---------

------for an easier way- but takes longer to work-sprinkle some sieved compost or soil over the area and the grass will grow through-you have to do this in stages or you will kill off the grass if you cover it completely-but the grass needs to be actively growing for this to work- so not yet.

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